blank=True vs null=True in Django

null=True

• Database layer.
• Column accepts SQL NULL.
• Django represents the absence of a value as Python None.
• Needed for non-string fields (e.g., DateField, ForeignKey) to store "no value."
• Indexes and unique constraints treat NULL as distinct from every non-null value.

blank=True

• Validation layer.
• Model and form validation permit an empty value on save or submit.
• For strings, the actual value stored is '' (empty string) unless null=True is also set.
• Has no effect on the SQL schema.

Common patterns

• String fields: blank=True, null=False → empty string stored, forms omit value.
• Non-string fields: blank=True, null=True → database NULL used, validation allows omission.
• Mixing null=True, blank=False rarely useful--database allows NULL, but validation rejects empty input.
• Leaving both as False enforces mandatory data at both database and validation levels.

Key distinctions

• null controls storage; blank controls validation.
• Database NULL ≠ empty string; choose one to avoid ambiguity.